Peter Lee, executive director of Covered California, is participating in a discussion Thursday with his board and other healthcare experts about 2017 exchange enrollment and the future of the Affordable Care Act in the aftermath of Donald Trump’s election to U.S. President. Trump has vowed to amend, repeal or replace the law.

SACRAMENTO — It was all hands on deck at Covered California’s monthly board meeting Thursday as leaders of the state insurance exchange and a panel of experts spent hours trying to divine a health care world according to President-elect Donald Trump.

The worst-case scenario is clear: On the campaign trail, Trump promised to repeal and replace the Affordable Care Act, President Barack Obama’s signature health care law that has insured 20 million Americans who had lacked health coverage.

Trump back-pedaled a bit last week, saying he would keep two key provisions of the law: allowing children to remain on their parents’ health care plans until age 26, and preventing insurers from denying coverage to Americans with pre-existing conditions.

But health care experts say many provisions of the Affordable Care Act, better known as Obamacare, cannot exist independent of federal funding.

Moreover, while Trump says he would protect those with pre-existing conditions, panel members on Thursday said they worried that he is relying on a preliminary alternative health care plan written by House Speaker Paul Ryan that critics say comes with major pitfalls. Ryan’s plan, for example, allows anyone with a pre-existing condition to keep their insurance — as long as there was no gap in their coverage. But if someone could not afford to pay their monthly premiums because of a job loss, their health insurance would disappear.

What seemed to sting the most to Obamacare supporters who addressed the board Thursday is the law’s success in the Golden State, where five million more Californians now have coverage.

“We did the best job in the country with enrollment,’’ John Bertko, the exchange’s chief actuary, told the board. He noted that there are three or more insurers in every one of Covered California’s regions. In comparison, about 25 percent of counties in the country have only one insurer.

Larry Levitt, a vice president at the Menlo Park-based Kaiser Family Foundation, said it’s worth repeating that the law had succeeded tremendously: The uninsured rates in both the nation (9.1 percent) and in California (8.1 percent) are the lowest they’ve been since Richard Nixon was president.

Yet, Levitt said, most of the public does not realize the drop has been because of Obamacare.

Today, 1.3 million Californians are enrolled in an exchange plan, the majority of whom receive hefty federal subsidies. An additional 3.8 million Californians also are enrolled under a provision of the law that allows single adults without children to sign up for Medicaid (called Medi-Cal in California), which provides coverage to the poor.

The prospect of losing their health plans has created widespread confusion and panic for both groups of Californians, even as many are in the process of signing up for 2017 health care plans.

Several speakers echoed Covered California CEO Peter Lee’s exhortation that the law’s benefits and requirements are still in place and that it’s very likely that their plans will not be interrupted in 2017 — and possibly 2018 — because it’s expected to take months for Congress to revise the law.

Lee said 44,885 newcomers to the exchange have selected health care plans as of Tuesday, while 263,462 other Californians have confirmed they either changed or renewed their health care plan for 2017. Enrollment continues through Jan. 31, and those who enroll by Dec. 15 will receive coverage beginning Jan. 1.

Still, the panel members laid out several troubling scenarios.

Levitt said the Republican Party’s platform to reduce federal spending, weaken regulations and lower taxes would likely result in fewer people getting coverage — and fewer comprehensive benefits.

Handing Medicaid funding to the states in bloc grants would give states more flexibility in running their health-care programs for the poor, but that would result in great financial risk for future cost increases, Levitt said.

Dr. Sandra Hernandez, president and CEO of the Oakland-based California Health Care Foundation, predicted that the debate by Congress over Medicaid and bloc grants will inevitably lead to a larger conversation about entitlement reform. She also worries that the coming changes in the law will occur at a time when consolidation and mergers in hospitals, physicians and health plans will contribute to higher health care costs.

Amid the gloomy tone of the day came some optimism from Ian Morrison, an internationally known author, consultant and speaker who specializes in long-term forecasting with a particular emphasis on health care.

“Coverage is going to change,” he said, though “repeal and replace will be incremental.’’

But if the Republicans significantly erode the health insurance of millions of Americans, he said, there could be serious political consequences.

Quoting Gen. Colin Powell’s famous warning to President George W. Bush as the U.S. prepared to invade Iraq in 2003, Morrison said: “If you break it, you own it.”

If Republicans throw 20 million Americans off their health care plans, “it may not go over well in the 2018 election,” he said. “And that is encouraging.’’